To make a homemade crossbow you will need:
* A block of non-resinous wood species, size 700x10x40 mm.
* The second leaf spring of the car Moskvich.
* Profile pipe 50x50x2 mm. 10 cm long.
* Profile pipe 15x15x1.5 mm.
* A small piece of sheet metal 2 mm.
* Metal stainless steel 4 mm thick. and 0.5-1 mm. (for the descender).
* Steel corner 50x50x4 mm. 35 cm long.
* Bar D = 8 mm. length 40 cm.
* Bolts with nuts D = 8
* Stainless steel molding from the VAZ-2106 door 2 pcs.
* Metal rollers 2 pcs., Glass lifting mechanism from the door of a VAZ car.
* Rope D = 3 mm. 3 m long, two terminal loops.
* Epoxy resin, wood stain, wood varnish for outdoor use.
* Two small springs (tension).
* A dozen nails for roofing material, one nail dvuhsotka, tube D = 6 mm., Small washers.
We will use the following tools:
*Welding machine.
* Hand circular saw.
* Electric drill with adjustable speed, carbide drills for metal D = 3, 5, 8, 10 mm.
* Grinder, cutting discs for metal, grinding discs for wood.
* Keys, pliers, screwdriver, vise, narrow chisel, knife.
* File, sandpaper.
* Goggles.
Item 1. Making a stock.
Take a well-dried wooden block, mine was made of birch, sketch a bed on it. We make each stock size for ourselves (for our height), and the stock, depending on the length of the arrows that you will use. I use 440 mm arrows, but I had to save money on the stock, I left only 300 mm, the total length turned out to be 740 mm, I didn't dare to do it anymore.
We will draw a marking for the selection of the guide, for the feathering of the boom, width 5 mm, depth 10 mm.
Using a circular saw, cut out the groove to the full length, up to the end of the trigger (lock).
It should look something like this.
Using a drill D = 12 mm. choose a cavity for the trigger, level the ledges with a chisel and a knife. We drill a hole for the trigger, grind it with a chisel and a knife.
Item 2. Making a lock or trigger.
Let's take the "nut" type as the basis of the lock. To prevent anything from rusting, we will use stainless steel, take a sheet with a thickness of 4-5 mm, if we cannot find one, make a type-setting of several sheets glued together and riveted. We draw the shape of the parts on the metal.
With the help of a cutting disc and a grinder, we cut out according to the marking of the workpiece.
In the center of the "nut" we will drill a hole for the axis of rotation D = 6 mm.
We process all sides with a file.
We sand with sandpaper, achieving a completely smooth surface.
It should look something like this.
We grind the rest of the castle elements, whispered.
I lengthen the trigger with two thin sheets of stainless steel, fix it on homemade rivets.
On the grinder we achieve the desired shape of the workpieces.
We make the case of the trigger from a thin sheet of metal.
We drill three holes D = 2.5 mm in the sear body, one for the mounting axis and two for mounting the springs.
Reattach the trigger spring into place.
Let's see how the cocked parts become on the table.
And as after the shot.
We attach one side of the case to the inside of the mechanism and drill in place of the hole for all the axles.
From a dvuhsotka nail, 6 mm in diameter, we will make an axis for the "nut".
Saw off the sharp end of the nail.
We measure the length of the future axis, saw off.
From thin nails for roofing material, we will make the rest of the rivet axles. Using a grinder, remove the ebb from the nail heads.
They will now fit well to the body.
Install the sear on the axis in the body, use the intermediate washers.
Saw off the extra length of the nail, leaving 1 mm each. on both sides for rolling.
Using an anvil, roll the end of the axle with a hammer.
We drill a hole for the axle with a spacer, for attaching the spring sear.
From a suitable tube, we saw off the spacer sleeve onto this axis.
We move to the side one side of the body.
We install the axle, the bushing and hook the spring.
Putting the halves of the case together.
Saw off the excess length, leaving a protrusion of 1 mm. under the hammer.
Let's roll.
Now you can put the largest rivet pin of the lock. We combine the holes.
Let's take the previously measured and sawed off axis D = 6 mm., Immediately with a little knocking hammer on one side.
We put in place.
And we will also roll over, the main thing is not to overdo it, so as not to jam the movable mechanism inside.
Item 3. Installation of the lock mechanism in the stock.
If something prevents the lock from sitting well in place, we modify it with a chisel or knife. After installation, we check how the trigger goes.
If everything is fine, you can drill holes for the mounting screws and screw them into place.
Now we need decorations from the VAZ-2006 door, they are also made of stainless steel, which is very good. To give them additional rigidity, epoxy resin was poured inside.
After complete hardening, in a day, we will drill four holes D = 3 mm in each, for fastening screws.
With a large drill we will make recesses for the heads of the self-tapping screws so that the bowstring cable does not catch on when it slides along it.
Use fine emery paper to polish the holes to remove any burrs that damage the cable.
We install the finished guides on the bed.
We make sure that the screws do not go through in thin places.
We check that the lock goes without hooks on the guides.
Item 5. Making an arch or shoulders.
From the same donor doors, we extract the rollers of the glass lifting mechanism with the help of a grinder.
From them we will make blocks for the shoulders, and the arc itself from the second leaf of the spring, an old Moskvich car.
We will make pads for attaching the spring to the stock.
For this, from a corner of 50x50 mm. we will cut out the constituent elements in order to assemble by welding, here is such a mount (block).
We will process the welded seams with a grinder. Let's drill the fixing holes D = 10 mm. under the bolts.
According to the finished sample and the size of the resulting block, we make grooves for fastening in the bed. Trying on the landing, achieving a tight approach and attachment. According to the estimated position of the future bowstring, we outline and make a through groove in the sidewall of the stock, 70 mm long. 10 mm wide, the lower bowstrings will go here.
Bend and weld the leg brace (stirrup).
Ears for blocks.
From a profile pipe 50x50, we will make lugs for attaching the rollers-blocks to the arc (spring).
The most difficult thing in making the spring itself from the spring at home is to drill holes in it. It is necessary to drill with a drill at low speeds so that the drill does not burn, constantly use water. If possible, drill with drills of different diameters, from thin to thick in increments of 0.5-1 mm., Constantly sharpen the tool.
We attach the brackets to the short M8 bolts, grind the hats.
We fasten the spring to the block with two M8 bolts, followed by small welding along the edge of the attachment.
Now you need to open the bed with varnish and dry it.
We install a block with an arc on the bed, we plant it with a hammer for a tight fit of the metal-tree.
Insert and tighten the bolts on the M8.
From long M10 bolts, we will make axle bolts reduced in length with a short thread for blocks.
Take a tube from the anchor and make spacer sleeves for the axes of the blocks out of it.
Let's drill holes D = 10 mm in the ears. to install blocks. Install the rigid loop ends on the cable.
We install a block with a cable on one side of the shoulder. Do not tighten the nut strongly so as not to jam the rotation of the roller.
In the nut and bolt we drill a hole for the stud.
We install the hairpin and tighten it with a nut in the direction of unscrewing.
We push the cable through the hole in the bed and do the same with the installation of the roller on the other side of the shoulder.
Point 6. The upper part of the castle.
From a profile pipe 15x15 mm. saw off two pieces of 120 mm. We cut out two (G) shaped blanks from sheet metal with a grinder, one rectangular plate (to the top) and a triangle (to the back).
We weld all the parts together by welding, we clean the welding seams with a grinding disk so that we get a kind of one-piece part.
From the old folding steel meter, we make an elastic boom holder.
The photo shows the mounting bolts for the telescopic sight rail.
The same is true, only the bolts also clamp the boom holder at the same time.
The sight rail itself (dovetail) is made of the same sheet metal 2 mm., With the sharpened sides for mounting the optics.
A square pad is visible on the optics rail to raise the rear part and thereby tilt the sight downward for correct aiming at a target beyond 25 m.
We install the lock bracket on the stock and drill holes for fastening, self-tapping screws and an M6 bolt.
We tighten small self-tapping screws so that they do not go out into the feathering channel of the boom.
We tighten the self-tapping screw on the back.
Additionally, we drill the hole and install the last bolt.
Installing the optical sight.
A hunting crossbow is a fairly effective weapon that, if necessary, can serve as a worthy replacement for a rifle. The main advantage of the weapon is the noiselessness of firing. Therefore, in the course of its use, it is rather difficult to scare the beast.
Design features
What does a hunting crossbow consist of? The photos presented in this material allow you to see that the following components can be distinguished in it:
- The body is the main power unit, which receives loads when lowering the bowstring. Serves as the basis for the installation of functional parts.
- Pads are part of the structure for installing bowstring tension arcs.
- A stock is a part of a crossbow that is used to place an arrow.
- A bowstring is a functional part that serves to set in motion the projectiles used.
- The shoulders are an elastic structural element that gives off energy when the bowstring is pulled.
- The stirrup is a part that facilitates the loading of the crossbow.
- The trigger mechanism is a device due to which the lock is opened and the bowstring is released when fired.
- Sight - mounted on a crossbow to facilitate targeting.
Hunting crossbow with wooden shoulders
It is the simplest design. As follows from the definition, the shoulders here are made of wood. Such a crossbow cannot be called a model of reliability. Products in this category are frankly short-lived and therefore are not in very high demand. Most often, such a hunting crossbow is used as a collection, decorative weapon.
Metal arched crossbow
An extremely common option. Hunters pay attention to such crossbows because they demonstrate high power when firing. Hunting bows and crossbows with metal arcs are not only suitable for training, but also for use in the field when tracking down prey. For manufacturing, both solid arcs and composite structures are used, which are assembled from several symmetrical parts.
Recursive Crossbow
The classic version with curved shoulders. Such a hunting crossbow is an extremely easy-to-use and easy-to-use device. It has small dimensions and improved performance. Easy to disassemble and transport.
Recursive crossbows contain reinforced shoulders, the pulling force of which can reach about 50 kg. This, in turn, opens up opportunities for hunting small and large game.
Block crossbow
The design includes a whole system of eccentrics, thanks to which the process of loading the weapon is facilitated and the boom is accelerated. Compared to recursive models, the block hunting crossbow is more compact. The power figures are also at their best here.
Small dimensions are provided by the installation of short arcs. The use of this solution contributes to the easy passage of the owner of the weapon of the areas covered with thickets and bushes.
The characteristics of a block-type hunting crossbow provide a simple bowstring platoon and insignificant recoil, which is achieved due to the rational distribution of the force vector.
type
- due to their reduced dimensions, they are extremely convenient for transportation weapons;
- have high power and allow you to hit targets at both medium and long distances;
- They have a lower destructive power compared to block systems, but they throw out arrows at a higher speed;
- in addition to arrows, they can release darts, harpoons, metal balls.
Sights
The main feature of crossbow shooting is a significant displacement of the aiming line. In other words, after the shot is fired, the projectile begins to gravitate rather quickly to the ground. Therefore, it is advisable to install optics with a special crossbow net on such weapons. For effective aiming at the target, it is enough to equip crossbows with optical sights with a 4x zoom.
Some hunters prefer collimator systems, which are also quite effective. Moreover, this option makes it possible to hunt both in the daytime and in the evening. Reflex sights are extremely convenient to use when aiming at moving targets.
DIY hunting crossbow
Having decided on the necessary parameters and characteristics of the future weapon, it is worth moving on to the development of the corresponding drawing. As a sample, you can use a ready-made scheme or draw up the latter yourself. Be that as it may, a do-it-yourself hunting crossbow will eventually have to be customized.
During the preparation of the drawing, it is worth focusing not only on personal wishes, but also take into account the availability of the necessary materials, proceed from their cost, the complexity of processing.
How to make a hunting crossbow with your own hands? Usually, to begin with, a bed is prepared, on which the shoulders, stirrup, guide, and trigger are subsequently attached. Arcs are a difficult element for self-production. Therefore, in some cases, it is better to purchase them ready-made.
They will help to make hunting drawings, examples of which are shown in the photos below.
Frame
The base on which the bed and shoulders of the product are fixed is the body. It is advisable to cut it out of a metal blank with a thickness of about 2.5-3 mm.
In the central part of the body and at the end, the crossbow stock is fixed with bolts. The use of such a solution contributes to the rapid assembly of weapons to bring them into combat condition and disassembly during transportation.
A stirrup is welded to the body at the bottom. The latter provides the ability to hold the crossbow with the foot while pulling the bowstring. It is recommended to use wire 6 to 8 mm in diameter as the material for the stirrup.
Shoulders
The material for the manufacture of a structural element can be an automobile spring. In such metal arms, semicircular bolt recesses are made, with which the part will be screwed to the body.
A common opinion is that the use of metal springs as a basis for the manufacture of shoulders is a rather dangerous solution. And in fact, when using a homemade crossbow in a low ambient temperature, the probability of breaking the part increases, especially in the attachment points. Such cases are accompanied by the release of small fragments. Therefore, the idea should be applied at your own peril and risk.
Blocks
Ready-made drawings of a hunting crossbow often include block devices. The latter relieve tension and give an advantage in strength. It is easier to bring such a crossbow into a combat state than by simply connecting the ends of the bowstring with the ends of the shoulders. Moreover, during the descent, the starting speed of the arrow increases, which is reflected in the increase in the range of the weapon. The main disadvantage of installing a block system is the complexity of manufacturing and an increase in the total weight of the crossbow.
Bowstring
As a bowstring, you can use a metal cable with a diameter of about 2-3 mm. A thicker bowstring will be more difficult to attach to the weapon, and a thin one will stretch as the product is used.
To fix the bowstring at the ends of the shoulders, it is enough to make a regular loop. It is better to place pieces of leather or any other dense material under the cable bindings. This solution allows you to avoid chafing the bowstring in contact with metal shoulders.
Lodge
For the manufacture of the part, you can use an easy-to-process wooden blank in the form of a board with a thickness of about 30 mm. It is worth noting that, despite the high strength indicators, oak is not very suitable for these purposes due to its significant weight. As for spruce and pine, the latter are not sufficiently resistant to mechanical damage and warp on contact with moisture. Therefore, the type of wood should be selected depending on the goals and conditions for the future use of the crossbow.
How to make a hunting crossbow truly practical? During manufacturing, special attention should be paid to the guide in the form of a groove for the boom, which must be tried to be made as even, smooth and polished as possible. The condition of the groove is largely reflected in the accuracy of shooting. It is desirable that the width of the stock is equal to the diameter of the arrows used. You can cut it with a circular saw.
It is rational to use a spring as a means for holding the arrow, which will press the projectile against the bed and will not allow the latter to slip out of the groove before the shot is fired.
Trigger mechanism
The material for the manufacture of the part will serve as sheet metal. It is desirable that its thickness is at least 6-7 mm. A drawing of the mechanism is presented in the following diagram:
All parts are placed directly in the stock. Here, a special socket is cut out, through holes are made under the axis of the mechanism, on which the descent elements are subsequently installed. An example of setting the trigger is shown in the figure below.
Sighting optics
As a crossbow sight, you can use factory optics from firearms. A fairly practical solution is the use of front sight and rear sight. With the help of the latter, vertical corrections can be made. It is convenient to perform horizontal adjustments using a front sight fixed at the intersection of the shoulders and the stock.
To ensure the convenience of transporting the crossbow, it is worth making the sighting device removable. To do this, a so-called Picatinny rail can be installed on the weapon, which provides the ability to mount individual factory-assembled sights.
Finally
The hand-made manufacture and operation of a hunting crossbow is a rather radical solution. Often, in the absence of experience in this kind of activity, the quality and reliability of a homemade device leaves much to be desired. In reality, even factory-made budgetary crossbows, which cost about 3000-4000 rubles, turn out to be much more effective, convenient and practical compared to the creations of their own hands.
As you can see, making a hunting crossbow is quite realistic. However, by purchasing a weapon in a specialized store, the user receives guarantees of its safety and reliability of assembly. When operating a homemade crossbow, you can only rely on yourself.
It told how to make a crossbow with your own hands from scrap materials. A shot in such a crossbow is carried out due to the elasticity of the bow. Moreover, the bow of the crossbow itself can be made from almost any elastic materials. As in the article, you can use spring strips from an old mattress, you can pick up a grinder and make a crossbow from a spring. Today, composite materials are often used - fiberglass, carbon fiber and epoxy adhesives to make elastic shoulders for homemade crossbows.
But, the other day I came across an old bed, or rather a net with springs.
I immediately thought - elasticity is used in the crossbow, but not only the plates from which the bow is made, the springs also have a large reserve of elasticity. The simplest example of using springs to launch a projectile is air guns. So the crossbow can also be made on springs!
I went online and saw - yes, spring crossbows have existed for a long time and are made by craftsmen!
Here is a photo of a spring crossbow with one spring.
And this crossbow has two springs - each on its own shoulder.
Here is a shot from the spring crossbow in the video.
But most of all I liked the design in which the spring is located in the stock of the crossbow.
With this arrangement of the spring, the dimensions of the crossbow become minimal and it can be used in the forest and it is quite easy to carry it.
Shooting from a spring crossbow is carried out in the same way as from a regular one.
For ordinary hunting, the tension of the bowstring of the crossbow of 35-40 kg is enough. This is not my idea, this is the data of a standard hunting crossbow of the Middle Ages.
But if desired, the tension force can be easily increased by installing a more powerful spring or adding a couple more to the existing springs. Fortunately, there are 14 of them on one thrown out bed.
By the way, it is not necessary to use tension springs; you can also use the opposite effect - energy storage when the spring is compressed. Fortunately, today there are a whole bunch of different shock absorbers. You can use a spring from the shock absorber of the front wheel of a bicycle, where they are very stiff on inexpensive models, only a big man weighing 130 kilograms can push them.
And also - springs can be used not only on crossbows. Here's an example of using the tensile force of the springs on a homemade bow.
It seems to me that making such a homemade crossbow on springs is not a problem. The design is not more complicated than usual, but there is no most important problem - finding good elastic steel on the shoulders of the crossbow bow.
The second advantage of the spring crossbow is that the design can provide for a change in the tension of the bowstring by increasing the number of springs. As a result, it turns out that from the same crossbow you can shoot both light wooden bolts for hunting and heavy "armor-piercing" pieces of reinforcement. I really have little idea of a situation in which such devastating bolts will be needed, in ancient times solid-forged bolts were used to defeat a knight in heavy armor, and today's bulletproof vests without titanium inserts (with titanium this is the "antikalash" class) are easily pierced with a knife.
But the very opportunity to shoot through a brick wall is interesting :)
Also about making crossbows:
why111 11-03-2013 13:16
Hello ladies and gentlemen.
I turn (we are not local) to professionals with this question. There is a desire to think about a spring arrow, and it is planned to use a coil spring, such as in a pneumatic rifle.
One of the options is the "Rustle" bow, but I want to do without the bowstring. How realistic is this theoretically? There are two options so far.
1. The spring directly accelerates a heavy arrow at a low speed, but due to its mass, the projectile has a high penetrating ability, even at a distance of up to 25 meters. By the way, once I did this in the form of a toy, shot electrodes (cross section 5 mm), flew up only 20 meters, but up to five meters it seemed to come out powerfully.
2. Using blocks that increase the speed, for example, a chain hoist. Those. a short spring is compressed by a block of five "wheels", five are reciprocating, a cable passes through them, which accelerates the projectile.
Thanks in advance for your answers.
nixxx 11-03-2013 15:08
Can I guess ... For self-defense?
why111 11-03-2013 16:39
Fear God! Self-defense with self-made melee weapons of throwing action - yes, it is better to immediately confess. For self-defense, there are gas cartridges and, at worst, household knives. everyday life. destination.
No, of course it is, for the soul.
Juris 11-03-2013 17:01
Yes, if such a shooting mechanism had been invented, it would have been produced industrially and sold in weapons stores. At the moment there are compact enough powerful crossbows. Then you will have to shovel the gunza and look for archers with crossbows on the shape. You can find some interesting schemes with springs. and pulley blocks. Even on our forum there were suggestions with diagrams and drawings. You need to search to read, maybe you will find something interesting.
why111 11-03-2013 17:08
Those. impossible? Honestly, the forum seemed to be overlooked diagonally, but unfortunately I can't read it for two weeks. I thought maybe someone's inquisitive thought had already thought about this topic.
Juris 11-03-2013 17:11
Or watch the video from our catopult generalsimo Joerg Sprave. He has a lot of videos with different firing mechanisms. He may give you an idea.
Juris 11-03-2013 17:17
Everything is possible, the main desire is to know your goal.
why111 11-03-2013 17:22
Thank you, I met his video, the head works well, although not ours)
why111 11-03-2013 17:55
Somewhere about such a thought was, only simpler, of course.
I thought about one spring, a more compact form (not a gun type, but possibly a pistol one), well, a spring in a case and for compression, not tension.
9_Gramm 11-03-2013 19:38
Do you understand dear Why, all these systems are not effective (excuse my clumsy Russian) Springs themselves are slow, plus they also have to drag their own weight. Also, all these blocks and pulleys are also heavy and cumbersome. At the moment, of all the throwers (not propelled by hot gases), the slingshot with good latex is probably the most productive thing. If we count the energy put into it and the cost and deduct the result obtained from this. Well, maybe some sling would argue with her. (A good bow is inferior in size, in terms of price and cost of the shot. And of course the energy invested in the shot, you have to pull it for real)
Well, here's an example, here in this video you see the "Raptor" block set in motion with strong rubber. (The springs were not taken, since their efficiency is worse than that of rubber)
This apparatus has a tensile force of up to 80 lbs (approximately 36-38 kg) and propels a 10 mm ball at a speed of 140-150 m / s
Wow, that's pretty good. But consider the energy consumption in this thing. Firstly, in order to stretch 36 kg, you need good health (I was at Jörg's place and also shot from this thing, I'll tell you to pull oh oh how it should be)
Then the dimensions, and finally the cost of this thing (I don’t know for sure, but it’s probably worth 800 dollars.
If you try to do such a thing yourself, it is unrealistic. Or you need to have an excellent lathe at home. Or spend big money on the industry. Then where to shoot? In the garden? How to hang around with him? With this size and weight, it is not a very convenient thing for a walk.
Well, now we are making a slingshot at home from hazel and a purchased fitness band.
Price? A penny, anyone can afford.
Dimensions? Fits quietly in your pocket, you can clench it into a fist.
Where to shoot? Anywhere, the thing is not heavy. You can take and drag anywhere. It is not striking, no one will stupidly look askance at you. The extreme quickly gets out of sight.
How much energy do we spend when firing? With a tensile force of ten kilograms with good latex in Albatross, we will disperse the same 10 mm balloon well
at 110 m / s, maybe more if you try. How many shots of 10 kg are we going to stretch (even a teenager can pull it)?
How many shots will we make with the "Raptor" in 36 kg stretching?
Jörg, after 10 shots, is already breathing with his tongue out and letting off steam like a locomotive. And he is a really strong man. And innoy and once will not pull.
Well, roughly the same will happen with your spring gun. You will toil to do. A heavy bulky piece will come out. And if it will shoot at least a few meters per second better than a slingshot, then respect to you.
With all these homemade guns, this is usually the case, if you look closely, that is, something is already more efficient and cheaper than you will invest in your brainchild. It's just not worth the candle.
why111 11-03-2013 19:50
Thank you so much for the detailed answer. Of course you are right. It's just that my desire to do something is itching to do something, but I've been thinking about this for a long time. And the spring is still more durable than plastic.
By the way, after studying the forums a little, I saw that a lot of archers and crossbowmen periodically think about this. Good, working models come out from a few. Okay, let's see, maybe something will come up.
9_Gramm 11-03-2013 20:08
Well, if only to play around, then you can do anything And in the end, throw it away without regret if nothing sensible comes out. If you fix something, then do not hesitate to show.
Evil 12-03-2013 14:47
2 why111
Hell fought for a gas spring, with an ultralight stem.
why111 12-03-2013 15:01
Well, gas is for the pros, I still think more budgetary and simpler, just to see what it can get out.
Evil 12-03-2013 15:47
2 why111
Yes, there is nothing complicated there - and the usual twisted itself is heavy and inert with a shackle.
+ how to cock?
why111 12-03-2013 16:47
Well, the simplest option is similar to the picture above. Cocks like a typical crossbow. And a long time ago I made one that is cocked by an arrow, it had to be pushed against something.
why111 12-03-2013 17:48
Well, that means that the principle still works, the main thing is to design. True, there is no machine park to make products like by reference.
Juris 13-03-2013 15:57
In general, yes, the topic is interesting. But at home it is difficult to do it. Again, you can only see the Yorg system made of wood, which can really be done. Or look for a pitbull crossbow type in the internet and all its components. It takes a lot of tests and funds. It's easier for now. make a good slingshot or upgrade a compact Izhik fracture.
delete 13-03-2013 23:55
yes indeed, thoughts visit many about compact mechanical crossbows
well, many are stopped by the very first factor, where and how to do it all
and whether it is necessary, since it is very difficult to force to issue normal parameters
the design turns out to be cumbersome and heavy, since it turns out that the spring must be set for a compression force of at least 100 kg.
you can, of course, first start with models made of wood or from what else, on which you can work out a preliminary scheme, choose the optimal shape of the block, if the spring is meant to be weaker
but again this is not for everyone
for me, for example, it will not be difficult and generally not very annoying if my next project in terms of spring mechanical bows or crossbows in the form of a layout will be checked and tested for professional suitability for six months, or even a year
I'm ready to wait, but find the best option
so what could be better to really do a slingshot for now
and the spring pushing the projectile directly will have very, very weak parameters
well, in addition to the video of the foreign Kulibin
http://www.youtube.com/watch?v=AXwTZLrtsRA
9_Gramm 14-03-2013 02:05
delete 14-03-2013 07:56
but he tested his theory
first, the spring in this design will not give the boom normal speed
second, cocking with a screw and nut is a very good way
why111 14-03-2013 13:02
quote: second, cocking with a screw and nut is a very good way
With a powerful spring - yes, but you need a wide-pitch thread, trapezoidal, and a standard folding gate. You can consider a Chinese threaded jack as a donor.
9_Gramm 14-03-2013 17:49
The screw and nut cocks well, yes. But don't forget the cocking time! After five shots you have to go home, the night is outside
Dear lovers of homemade weapons, today I want to bring to your attention not an ordinary crossbow that uses mechanical tension on the shoulders to throw an arrow, but something completely different. Namely, a spring-vacuum crossbow, which can be used not only for land, but also for spearfishing. It is compact, comfortable, allows you to hunt in dense vegetation, the vacuum energy greatly increases the range and speed of the arrow. Schemes of this weapon were found on the Internet.
To begin with, let's touch on a brief description of the crossbow device. This weapon has the following main components and mechanisms: crossbow stock 1 (Fig. 1; 3), shoulders that are fixed motionless in front of the crossbow stock strictly perpendicular to its axis 2 (Fig. 1; 2), rotating guides, bowstring straightening mechanism ... In the lower part of the crossbow bed, blocks are immovably fixed: receiving 3 (Fig. 2), which are fixed with a corner 4 (Fig. 2) to the underside of the shoulders. Moreover, the angle between this pair of blocks must be strictly ninety degrees. Guide blocks 5 (figure 2) fixed through the stirrup 6 (figure 1; 4) in front of the vertical plane of the crossbow arms. Another pair of blocks - bowstring 7 (Fig. 1; 2; 3), they are located at the edges of the crossbow arms. Through these extreme blocks passes a cable 8 (Fig. 1; 2; 4), which is actually the bowstring 9 (Fig. 1; 2). On the crossbow stock itself there is a special mechanism that holds the bowstring 10 (Fig. 1). The stops 11 are attached to the bottom of the bed; 12 (Fig. 3). Between them there is a pipe 13 (Fig. 3; 4; 5), in which the spring-vacuum mechanism is located.
Now let's see how this mechanism works. First, let's analyze the device of this mechanism for compression. Inside the through pipe 13 (Fig. 3; 4; 5) there is a helical compression spring 14 (Fig. 4; 5) and a vacuum piston 15 (Fig. 4; 5). Two parallel cables 8 are rigidly attached to this piston (Fig. 4; 5), which are threaded through a spring. At the end of the pipe there is a rubber gasket, the so-called emergency shock absorber 16 (Fig. 4; 5). There is also a fuse 17 (Fig. 5).
In the sealed chamber of the pipe 22 there is a pump 19 for pumping out excess air and changing the power of the weapon, plus a pressure gauge for the pressure of the vacuum chamber 20, which shows what vacuum is in the chamber, and an instant discharge valve 21, which serves for the safety of the cocked weapon. When it is opened, the pressure in the chamber will be equal to atmospheric and spontaneous firing will not occur.
As you can see from the description of the device - the weapon is quite serious and to make it yourself, you need to invest a lot of work and brains.
How does this unique weapon work?
When we pull the bowstring 9 -> 9a (Fig. 1), the cables pull the piston back. The blocks begin to rotate guiding the cable. At the same time, the volume of the vacuum chamber increases and as a result of this increase, the air discharge in the chamber increases. The piston moves until it is blocked by a safety catch.
To fire, turn off the fuse, bowstring 9 -> 9a (Fig. 1) is released and the spring begins to move the piston forward, which pulls the cables 8, the blocks, rotating, direct the cable, bowstring 9 -> 9a (Fig. 1) sharply straightens up and a shot is fired. In this case, compressed air is thrown into the decompression hole located at the stop 12. If the shoulders have a span of forty centimeters, and the bowstring has a working stroke of thirty centimeters, then the spring's working stroke will be seventeen centimeters.
Unfortunately, I was able to find, though detailed diagrams of the device of the vacuum-spring crossbow, but without any specific dimensions. Therefore, this weapon is not capable of being made by every DIYer, but only by those who have some technical knowledge and design thinking. Good luck with your endeavors.
Fig. 1 is a crossbow top view.
Fig. 2 is a front view of a crossbow.
Fig. 3 is a side view of a crossbow.
Fig. 4 is a crossbow bottom view. (the pipe is conventionally not shown in the diagram)
Fig. 5 - a spring mechanism in operation with a compression spring
Fig. 6 - spring mechanism in operation with a tension spring
Fig. 7 - the action of the mechanism using the work of the vacuum chamber
1 - crossbow bed, 2 - fixed crossbow shoulders, 3 - receiving pair of blocks, 4 - corner, 5 - guiding pair of blocks, 6 - stirrup, 7 - bowstring-forming pair of blocks, 8 - rope, 9 - rope-bowstring, 10 - mechanism holding the bowstring, 11 - stop, 12 - stop, 13 - pipe, 14 - compression spring, 15 - piston, 16 - rubber emergency shock absorber, 17 - fuse, 19 - pump for additional air pumping, 20 - vacuum pressure gauge, 21 - instantaneous valve discharge, 22 - sealed vacuum chamber
P.S.
The article is rewritten. The administrator is not responsible for the accuracy of the information. Everything you do, you do at your own peril and risk.